This invention relates to aircraft, and more particularly, to a rotorcraft hybrid that incorporates a magnetic or electromagnetic vertical takeoff and landing (“VTOL”) system or an aircraft that uses a magnetic suspension and drive for a tail rotor or lift fan.
Conventional helicopters or rotorcraft are versatile aircraft that allow for vertical takeoff and landing and that offer reasonable amounts of vertical lift and horizontal speed up to the retreating blade limit. The basic helicopter configuration is the result of mechanical evolution that applied the present state of the art over many years. While the conventional rotorcraft offers many advantages, it still suffers from a number of disadvantages. For example, rotor blades are long but provide meaningful lift over only a relatively short segment at the ends of the rotor blades. This means that the center of the rotor area is not being effectively utilized. Also, because the hub about which the rotor blades rotate is relatively small, only a small number of airfoils may be used. Similarly, because the rotor shaft is relatively small, the weight of the craft and any load carried may place significant stress on the shaft. These disadvantages severely restrict the lift capabilities of rotorcraft. Further, having the center of gravity displaced substantially below the center of lift leads to a relatively unstable configuration. Further still, the horizontal speed of conventional rotorcraft is undesirably limited by the retreating blade limit. Also, a tail rotor is needed for stability, and tail rotors of conventional helicopters suffer from a number of problems. For example, mechanical linkages, such as drive shafts and gears, that mechanically couple tail rotors to main engines add unnecessarily to the weight of helicopters and can cause mechanical and reliability problems.
Conventional fixed wing aircraft are versatile as well and offer many advantages. Aerodynamic advantages allow fixed wing aircraft to travel at greater speeds and carry heavier payloads. Still, conventional fixed wing aircraft typically lack VTOL capabilities. Hybrid aircraft such as the Harrier, Osprey, and Joint Strike Fighter have been developed in an attempt to offer a fixed wing aircraft having VTOL capabilities or very short takeoff and landing (“VSTOL”) capabilities. While these are remarkable aircraft, they too suffer from a number of shortcomings. For example, the vertical lift capabilities of these aircraft is quite limited and do not approach the vertical lift capabilities offered by many conventional helicopters, so they are poor candidates for transporting heavy payloads. Also, these aircraft are relatively unstable during VTOL or VSTOL maneuvering. Further still, mechanical linkages, such as drive shafts and gears, that mechanically couple lift fans and turbine engines can add unnecessarily to the weight of aircraft such as the Joint Strike Fighter and can lead to mechanical and reliability problems.